Previous studies have shown that practice in performing a selective attention task leads to improvement in ignoring task-irrelevant distractor stimuli (Kelley & Yantis, 2007). Performance in a color discrimination task was hindered by the presence (vs. absence) of irrelevant distractor stimuli (e.g. images of objects); these distractor interference effects were diminished with practice. Moreover these practice effects were shown to transfer to previously unseen distractor stimuli (e.g. new object categories), suggesting improvements in a general mechanism for ignoring distractors.

Here we report experiments testing the role of subjects' expectations regarding the probability of distractor presence, using Kelley and Yantis's color discrimination plus irrelevant distractor paradigm. Overall the results show that the practice effects were robust to a change in the probability of the distractor presence following practice. This indicates that improvements in ignoring distractors generalize not only across visual properties of the distractor items, but also across expectations about probability of distractor presence. This work provides a new demonstration of a general mechanism of attentional learning.